Electromagnetic brake control circuitry for elevator application

ABSTRACT

A brake system for an elevator car includes a multiple of brake segments for deceleration of the elevator car and a brake control circuit operable to control operation of each of the multiple of brake segments to passively sequence activation of each of the multiple of brake segments.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of provisional application Serial No 62/185,827, filed Jun. 29, 2015.

BACKGROUND

The present disclosure relates to an elevator system and, more particularly, to elevator systems equipped with an electromagnetic brake system.

In emergency stop (E-stop) operation such as during power interruptions, engagement of an electromagnetic brake system may result in passenger discomfort due to the abrupt deceleration. This may be particularly noticeable in a downward travelling elevator car, with the car being lighter than the counterweight (motoring run), when the brake forces and gravitational forces are in the same direction. Regulatory bodies have restricted the performance of electromagnetic brake systems to address these conditions.

In conventional roped elevator systems, the rate of deceleration is relatively low due to the relatively heavier cars, counterweights, and resultant drive machine inertia. In relatively more recent elevator systems, the elevator cars are much lighter and the overall system inertia is lower, which contributes to relatively higher rates of deceleration during an emergency stop event. This relatively high rate of deceleration may also result in belt slippage, which may be unacceptable under certain regulatory regimes.

SUMMARY

A brake system for an elevator car according to one disclosed non-limiting embodiment of the present disclosure can include a multiple of brake segments for deceleration of the elevator car; and a brake control circuit operable to control operation of each of the multiple of brake segments to passively sequence activation of each of the multiple of brake segments.

A further embodiment of the present disclosure may include, wherein the brake control circuit includes an electromagnetic coil and a snubber network for each of the multiple of brake segments.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network for each of the multiple of brake segments control a sequence to control the deceleration of the elevator car.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network includes a diode.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network includes a Zener diode.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network includes a resistor in series with a diode.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network includes a capacitor in parallel with a diode.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the snubber network includes a coil in series with a diode.

A further embodiment of any of the embodiments of the present disclosure may include, wherein stopping a flow of electrical current through the brake control circuit is operable to initiate engagement of the electromagnetic brake

A brake system for an elevator car according to another disclosed non-limiting embodiment of the present disclosure can include a first brake segment operable to apply a first brake torque at a first time in response to a first snubber network; a second brake segment sequentially operable subsequent to the first brake segment in response to a second snubber network, the second brake segment operable to apply a second brake torque at a second time subsequent to the first time; and a third brake segment sequentially operable subsequent to the second brake segment in response to a third snubber network, the third brake segment operable to apply a third brake torque at a third time.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the third time is subsequent to the second time.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the third time is about equal to the second time.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the first, the second, and the third brake segment are sequentially operated to stop 125% of a rated load of the elevator car.

A further embodiment of any of the embodiments of the present disclosure may include, wherein two of the first, the second, and the third brake segments are operable to stop 100% of the rated load of the elevator car.

A method of engaging an electromagnetic brake for an elevator system according to another disclosed non-limiting embodiment of the present disclosure can include sequentially controlling application of a multiple of brake segments for deceleration of the elevator car in response to the stopping of a flow of electrical current through a brake control circuit.

A further embodiment of any of the embodiments of the present disclosure may include, wherein sequentially controlling application of each of the multiple of brake segments includes controlling a response time of each of the multiple of brake segments.

A further embodiment of any of the embodiments of the present disclosure may include, wherein controlling the response time of each of the multiple of brake segments is effectuated by a snubber network.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the brake control circuit is passive.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the brake control circuit includes an electromagnetic coil and a snubber network for each of the multiple of brake segments.

A further embodiment of any of the embodiments of the present disclosure may include, wherein the response time of each of the multiple of brake segments is determined by the snubber network.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be appreciated, however, the following description and drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a schematic view of an embodiment of an elevator system according to one disclosed non-limiting embodiment;

FIG. 2 is a schematic view of forces acting on an embodiment of an elevator system under a regenerating run;

FIG. 3 is a schematic view of forces acting on an embodiment of an elevator system under a motoring run;

FIG. 4 is a schematic view of an electromagnetic brake for an elevator system;

FIG. 5 is a chart illustrating relationships for example electromagnetic brake systems with multiple segments;

FIG. 6 is a schematic view of another embodiment of an electromagnetic brake for an elevator system;

FIG. 7 is a schematic view of still another electromagnetic brake embodiment of a braking system for an elevator system;

FIG. 8 is a graphical representation of example operational values for the FIG. 7 braking system;

FIG. 9 is a schematic view of still another electromagnetic brake embodiment of a braking system for an elevator system;

FIG. 10 is a graphical representation of example operational values for the FIG. 9 braking system;

FIG. 11 is a schematic diagram of a braking control circuit for an elevator system; and

FIG. 12-16 are schematic diagrams of a portion of alternate braking control circuits for an elevator system.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an elevator system 10. The elevator system 10 includes an elevator car 12 located in a hoistway 14. The hoistway 14 includes one or more guide rails 16 interactive with one or more guide shoes 18 of the elevator car 12 to guide the elevator car 12 along the hoistway 14. A suspension member 20, typically a rope and/or a belt, suspends the elevator car 12 in the hoistway 14. It should be appreciated that although particular systems are separately defined, each or any of the systems can include otherwise combined or separated via hardware and/or software. It should also be appreciated that although one suspension member 20 is shown, multiple suspension members 20 may be utilized. The suspension member 20 is routed over one or more sheaves 22 thence to a counterweight 24 which may also be disposed in the hoistway 14. One or more of the sheaves may be a drive sheave 26, operably connected to a machine 28 to control the elevator car 12 along the hoistway 14.

The elevator system 10 includes a brake system 30 disposed, in one embodiment, at the drive sheave 26 to halt rotation of the drive sheave 26 and thus stop movement of the elevator car 12 in response to certain select conditions such as a power failure to the elevator system 10 or other emergency stop (E-stop) situations. While in the described embodiments the brake system 30 is disposed at the drive sheave 26, it is to be appreciated that in other embodiments the brake system 30 may be located at the elevator car 12 and is configured to engage the guide rail 16 thus stopping motion of the elevator car 12 in the hoistway 14.

In this embodiment, the brake system 30 is an electromagnetic brake that is normally in an open position when supplied with electrical power and the electromagnetic coils thereof are energized. This open position permits free travel of the elevator car 12. When, however, the supply of electrical power to the electromagnetic coils ceases, the brake system 30 engages and safely stops the elevator car 12. In typical elevator systems 10, the electromagnetic brake system 30 quickly stops the elevator car 12, but such rapid deceleration of the elevator car 12 may result in passenger discomfort.

With reference to FIGS. 2 and 3, two cases during operation of the elevator system 10 where the brake 30 may be applied to stop the elevator car 12 are schematically illustrated. FIG. 2 schematically illustrates the case where the elevator car 12 is lighter than the counterweight and is travelling upward. In this case, when the brake system 30 is applied, a brake friction force 32 and a gravity force 34 are in opposite directions. This has the effect of lowering a deceleration rate of the elevator car 12. FIG. 3 schematically illustrates the case where the elevator car 12 is lighter than the counterweight and is travelling downward when the brake system 30 is applied. In this case, the brake friction force 32 and the gravity force 34 are in the same direction, effectively increasing the deceleration rate of the elevator car 12 once the brake system 30 is applied. In this case it may be desirable to delay application of full brake torque by, in some embodiments, several hundred milliseconds, and soften the application of full brake torque to reduce the deceleration rate of the elevator car 12. This also facilitates reduction of the potential for slippage of the suspension member 20.

With reference to FIGS. 4-5, certain regulatory regimes may require electro-mechanical brakes to meet the following code requirements:

1—The brake system shall stop the car traveling down with 125% load; and

2—All mechanical components of the brake shall be installed in at least two sets such that if one set fails (N−1), the remainder shall stop and hold the car traveling down with 100% load.

In one embodiment, the brake system 30 includes a multiple of sequentially operated brake segments 40 a-40 c (three segments shown in this example). Each brake segment 40 a-40 c is separately operable and designed in relationship to the other brake segments to meet the desired code requirements. The multiple of sequentially operated brake segments 40 a-40 c facilitate emergency stop performance by increasing the time of which the code required brake torque is applied which, as a result, the deceleration of an E-stop is smoother and more controlled which is particularly advantageous in territories with frequent power interruptions.

In one example elevator system 10, an empty car weighs 1000 kg with a duty load of 2000 kg and a counterweight that weighs 2000 kg at a 0.5 overbalance. This results in a potential full car imbalance load of 1000 kg and a code requirement of 1500 kg for the 125% load and 1000 kg load stop for N−1 segments (FIG. 5). In this example, each brake segment 40 a, 40 b, 40 c of a 3-segment brake accommodates 500 kg to meet code requirement 1 of 1500 kg. That is, operation of all brake segments 40 a, 40 b, 40 c stop 125% rated load (1500 kg) to meet code requirement 1, while operation of N−1 segments 40 a, 40 b stop 100% load (1000 kg) to meet code requirement 2. This essentially softens the application of full brake torque to reduce the deceleration rate of the elevator car 12. This advantageously compares to a two-segment brake in which each of the two segments must provide 100% of the rated load (1000 kg) to meet code requirement 2 and thus results in a total brake torque of 2000 kg when both segments are operational. In other words, code requirement 2 for a two-segment brake results in a relatively high rate of deceleration during an emergency stop event when both segments are properly operational—which is typical. Notably, for a 4-segment and 5-segment brake, code requirement 1 necessarily controls to meet the 125% rated load requirement (1500 kg) (FIG. 5).

With continued reference to FIG. 4, each of the multiple of sequentially operated brake segments 40 a-40 c includes a separately operable electromagnetic coil 50 a-50 n that drives an associated brake caliper 52 a-52 c to control the timing and rate of the brake torque applied to a single brake disc 54. That is, each brake caliper 52 a-52 c is non-circular and interacts with a respective sector of the single brake disc 54. Each electromagnetic coil 50 a-50 c may be oval, curved, bean-shaped, circular, etc., and operates to control its respective brake caliper 52 a-52 c.

With reference to FIG. 6, each of the multiple of sequentially operated brake segments 40 a-40 c (three segments shown in this example) may alternatively include separate brake subsystems 42 a-42 c. Each separate brake subsystems 42 a-42 c include a brake disc 44 a-44 c, an electromagnetic coil 46 a-46 c, and an associated brake caliper 48 a-48 c. That is, each brake subsystems 42 a-42 c is self contained and separately mounted along an axis A on the drive sheave 26.

With reference to FIG. 7, another embodiment of the brake system 30 includes three sequentially operated brake segments 60 a-60 c that each include a separately operable electromagnetic coil 62 a-62 c (illustrated schematically) that drives an associated brake caliper 64 a-64 c to control the timing and rate of the brake torque applied to a single brake disc 66. In this embodiment, each brake segment 60 a-60 c is about equivalent in size, while each electromagnetic coil 62 a-62 c is different so as to vary the response time of the three sequentially operated brake segments 60 a-60 c. That is, each brake segments 60 a-60 c applies about equal brake torque but is released at a different time from the emergency stop (E-stop) initiation. The difference in the electromagnetic coil 62 a-62 c may be achieved by, for example, different characteristics in the coil design such as a number of coil turns, coil diameter, coil material, coil size, gap size, brake voltages, plate/housing materials, and/or combinations thereof. It should be appreciated that various characteristics may be defined to differentiate operation of the electromagnetic coil 62 a-62 c.

In this embodiment, the first brake segment 60 a drops relatively rapidly which almost immediately results in the rapid application of about ⅓ of the total brake torque. This rapid application of about ⅓ of the total brake torque prevents an over-speed condition (FIG. 7). Then, the second and third electromagnetic coils 62 b, 62 c are sized to sequentially release the associated brake segments 60 b, 60 c to complete a relatively smooth stop.

With reference to FIG. 8, upon initiation of an emergency stop (E-stop) operation, the first brake segment 60 a rapidly releases to prevent over-speed. Notably, the velocity of the elevator car 12 slightly increases but an over speed condition does not occur due to the rapid drop off of the first electromagnetic coil 62 a. Then, the second and third electromagnetic coils 62 b, 62 c drop sequentially thereafter to extend the brake activation time to achieve a relatively smooth stop. This sequential operation facilitates passive reduction to otherwise relatively harsh E-stops, complies with elevator codes, and requires no supplemental external power.

With reference to FIG. 9, another embodiment of the brake system 30 includes an auxiliary brake segment 80 a and two main brake segments 80 b, 80 c that each include a separately operable electromagnetic coil 82 a-82 c and an associated brake caliper 84 a-84 c to control the timing and rate of the brake torque application to a single brake disc 86. In this embodiment, the auxiliary brake segment 80 a is significantly smaller than that of the main brake segments 80 b, 80 c. In this example, the auxiliary brake segment 80 a is an about 30 degree segment, and each of the main brake segment 80 b, 80 c are about 115 degrees. The auxiliary brake segment 80 a may be sized just large enough to prevent an over speed condition. The over speed condition in one example is about 15% of a nominal e.g. 1 meter per second nominal speed.

With reference to FIG. 10, upon initiation of an emergency stop (E-stop) operation, the auxiliary brake segment 80 a relatively rapidly applies a brake torque sufficient to prevent over-speed. Notably, the velocity of the elevator car 12 may slightly increase but an over speed issue does not occur due to the rapid application of the auxiliary brake segment 80 a. Then, the second and third brake segments 80 b, 80 c drop essentially simultaneously thereafter to achieve a relatively smooth stop as compared to a conventional E-stop. This operation addresses local code challenges to a sequential brake drop (FIGS. 7 and 8) yet still facilitates passive reduction to otherwise relatively harsh E-stops.

With reference to FIG. 11, another embodiment of the brake system 30 includes a brake control circuit 100 to control operation of each of a multiple of brake segments 110 a-110 c (three segments shown in this example) of the brake system 30 and thereby passively sequence the brake drop of each brake segment 110 a-110 c to slow the deceleration rate in an E-stop event. Various regulatory agencies require electromechanical brake systems to become effective without supplementary delay after opening the brake release circuit. Diode and capacitor elements are not considered by the regulatory agencies to constitute a supplemental delay.

The brake control circuit 100 includes an electromagnetic coil 112 a-112 c, a snubber network 114 a-114 c, and a latching relay 116 a-116 c for each respective brake segment 110 a-110 c. It should be appreciated that although three segments are illustrated in this example, any number of segments will benefit herefrom.

The snubber networks 114 a-114 c are electrically arranged so that the electromagnetic coils 112 a-112 c are sequenced in time to slow a deceleration rate for an E-stop event. For example, the snubber network 114 a may include a surge absorbing component 116, such a Zener diode, a Metal Oxide Varistor (MOV) a Transorb, or other component in series with another diode 118 for relatively fast operation for the electromagnetic coil 112 a of the brake segment 110 a; the snubber network 114 b may be a resistor 120 in series with a diode 122 for the next sequential operation of the second electromagnetic coil 112 b of the second brake segment 110 b; and the snubber network 114 c may include a capacitor 124 in parallel with a diode 126 for the next sequential operation of the third electromagnetic coil 112 c of the third brake segment 110 c.

Upon initiation of an E-stop operation after loss of power, the snubber network 114 a minimally prolongs current flow for relatively fast operation of the electromagnetic coil 112 a of the brake segment 110 a. The brake segment 110 a thereby readily rapidly applies a brake torque sufficient to prevent over-speed. Then, the second and third electromagnetic coils 112 b, 112 c drop in accordance with the brake drop time provided by the respective snubber networks 114 b, 114 c, to complete a relatively smooth E-stop. This operation addresses local code challenges of a sequential brake drop yet still facilitates passive reduction to otherwise relatively harsh E-stops.

It should be appreciated that the snubber networks 114 ab, 114 c may be readily defined to provide the desired response for each brake segment 110 a-110 c. Alternative embodiments of the snubber networks are schematically illustrated in FIGS. 12-16 to provide a range of brake drop times such as a relatively fast Zener diode snubber network arrangement (FIG. 12); an adjustable speed snubber network arrangement with a variable resistor (FIG. 13); a slow snubber network arrangement (FIG. 14); an ultra slow snubber network arrangement with a capacitor and diode in parallel (FIG. 15); and an ultra slow snubber network arrangement with a diode and a coil or inductor in series (FIG. 16). It should be appreciated that various snubber networks, and various combinations thereof may be utilized to control the actuation sequence of each brake segment 110 a-110 c.

The latching relay 116 a-116 c of each brake segment 110 a-110 c may be simultaneously closed in an E-stop event such that a sequential brake drop of all brake segments occurs. Alternatively, only one or more the latching relay 116 a-116 c are closed such that the particular latching relay 116 a-116 c are set to a selected position at a beginning of an elevator car 12 run, based on, for example, a direction of elevator car 12 travel such as regen or motoring, and/or load imbalance between the elevator car 12 and the counterweight 24. That is, only particular brake segments 110 a-110 c may be set for a particular elevator run. While the latching relays 116 a-116 c are illustrated and described herein, it is to be appreciated that other switching mechanisms may be utilized in the brake control circuit 100. For example, in other embodiments a normal, non-latching relay or an electronic switch such as a mofset may be used. Further, an additional relay may be utilized in conjunction with the mofset to “latch” the mofset. This operation addresses local code challenges of a sequential brake drop yet still facilitates passive reduction to otherwise relatively harsh E-stops.

The use of the terms “a,” “an,” “the,” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content. 

What is claimed is:
 1. A brake system for an elevator car comprising: a multiple of brake segments for deceleration of the elevator car; and a brake control circuit operable to control operation of each of the multiple of brake segments to passively sequence activation of each of the multiple of brake segments.
 2. The system as recited in claim 1, wherein the brake control circuit includes an electromagnetic coil and a snubber network for each of the multiple of brake segments.
 3. The system as recited in claim 2, wherein the snubber network for each of the multiple of brake segments control a sequence to control the deceleration of the elevator car.
 4. The system as recited in claim 1, wherein the snubber network includes a diode.
 5. The system as recited in claim 1, wherein the snubber network includes a Zener diode.
 6. The system as recited in claim 1, wherein the snubber network includes a resistor in series with a diode.
 7. The system as recited in claim 1, wherein the snubber network includes a capacitor in parallel with a diode.
 8. The system as recited in claim 1, wherein the snubber network includes a coil in series with a diode.
 9. The system as recited in claim 1, wherein stopping a flow of electrical current through the brake control circuit is operable to initiate engagement of the electromagnetic brake
 10. A brake system for an elevator car comprising: a first brake segment operable to apply a first brake torque at a first time in response to a first snubber network; a second brake segment sequentially operable subsequent to the first brake segment in response to a second snubber network, the second brake segment operable to apply a second brake torque at a second time subsequent to the first time; and a third brake segment sequentially operable subsequent to the second brake segment in response to a third snubber network, the third brake segment operable to apply a third brake torque at a third time.
 11. The system as recited in claim 10, wherein the third time is subsequent to the second time.
 12. The system as recited in claim 10, wherein the third time is about equal to the second time.
 13. The system as recited in claim 10, wherein the first, the second, and the third brake segment are sequentially operated to stop 125% of a rated load of the elevator car.
 14. The system as recited in claim 13, wherein two of the first, the second, and the third brake segments are operable to stop 100% of the rated load of the elevator car.
 15. A method of engaging an electromagnetic brake for an elevator system comprising: sequentially controlling application of a multiple of brake segments for deceleration of the elevator car in response to the stopping of a flow of electrical current through a brake control circuit.
 16. The method as recited in claim 15, wherein sequentially controlling application of each of the multiple of brake segments includes controlling a response time of each of the multiple of brake segments.
 17. The method as recited in claim 16, wherein controlling the response time of each of the multiple of brake segments is effectuated by a snubber network.
 18. The method as recited in claim 16, wherein the brake control circuit is passive.
 19. The method as recited in claim 18, wherein the brake control circuit includes an electromagnetic coil and a snubber network for each of the multiple of brake segments.
 20. The method as recited in claim 19, wherein the response time of each of the multiple of brake segments is determined by the snubber network. 